No suit! As Arail5 states, khakis and a nice polo are great. You will see all measure of clothes on visiting candidates. My DS has hosted many. I have had two sons that did their visits before being offered appointments. You may not be able to participate in athletic type classes but may be able to work-out or go to athletic facilities with your cadet so bring athletic wear. You just want to look fairly nice when tending classes, but khakis and polo or button down are great. Have fun! these guys were where you are only a year ago…